Method and device for monitoring roller drilling tools

ABSTRACT

To determine the load distribution over the drilling head region of mining machines or roadheading machines the loads occurring at the individual roller drilling tools and simultaneously also the rotational running condition of the roller drilling tools are determined by determining the tangential deformations occurring at one of the races of a roller bearing associated with each tool. For this purpose, a measuring point with a strain gauge is associated with each roller bearing, that is, with either the outer race or the inner race of the bearing. With only this single measuring point, information is obtained on the magnitude of the load on the roller drilling tool and on its rotational running condition, this taking place via a great number of pulses per revolution. As a result, substantially more accurate information is obtained, as well as a simplification of the device from the constructional point of view, in comparison to prior devices.

BACKGROUND OF THE INVENTION

The invention relates to a method for monitoring the cutting or wartrollers, in particular of roadheading machines in mining and tunnelconstruction, by determining the loads occurring at the individualrollers. The invention also relates to a device for carrying out themethod with measuring points which are equipped with strain gauges andan evaluating unit.

Part-face and full-face heading machines which are used in undergroundmining and tunnel construction and equipped with roller drilling toolscomprise a drill head which works the entire face in the heading anddetaches the solid mineral. This extraction work is done with the aid ofcutting or wart rollers which are arranged at the rotating front disc ofthe drill head or the hood-shaped drill head. The cutting and wartrollers fragmentate the rock by high pressure and for this purpose theroadheading machine is braced against the sidewalls with prop claws orsupported correspondingly on the floor. To determine the loaddistribution across the drill head region of these heading machines theloads occurring at the individual roller drilling tools are measured bymeans of strain gauges. These measurements at the bearing pedestalshowever do not provide full information because they do not permit anyassessment of the rotational running condition of the roller drillingtools. The monitoring of the proper rotational condition of the rollerdrilling tools, which permits conclusions to be drawn on the wearbehavior and on sparking possibly caused by stationary rollers, musttherefore be carried out in parallel. For this purpose an additionalmeasuring point is employed which by means of a so-called cam pulseindicates each revolution of the cutting roller. A disadvantage in theknown method and also of the known device for carrying out the knownmethod is that separate measurements must be made, that separatemeasuring points are necessary, and that roller rotation stoppage ispossibly measured and reported only after a delay.

The problem underlying the invention is to make it possible to measurein combination and accurately the loading and the rotational behavior ofthe roller drilling tools of a heading machine or the like and toprovide a device suitable for this purpose.

SUMMARY OF THE INVENTION

The problem underlying the invention is solved in that tangentialexpansions are measured at the races of rolling bearings supporting theroller drilling tools.

By the method according to the invention it is surprisingly possible foreach roller drilling tool to simultaneously reliably monitor, by meansof a single signal, both the load applied to and the rotational behaviorof, the roller drilling tool. The appearance of the signal itselfindicates that no stoppage of the rotation of the associated tool hasoccurred, while the absolute magnitude of the signal is an indication ofthe magnitude of the load applied to its tool. The values determined inthis manner are substantially more accurate and simpler to transfer thanthose in the already known methods. As a result, a quicker and morereliable reaction to the operational behavior is possible. In regard tothe device, the problem is solved in that the measuring point isarranged in one of the races of the measuring bearing and is formed as astrain gauge. This solution is advantageous because the arrangement isthen of simple construction since only one measuring point need beprovided and observed for each tool. It permits the monitoring of allthe necessary functions and obtains the corresponding information.

The aimed for strain gauge measuring point introduced to a bearing makesit possible to determine reliably and simply, during a cuttingoperation, simultaneously, the necessary exact information on themagnitude of the loading of and on the rotational movement or standstillof the associated roller drilling tool. The characteristics of themeasuring signal depend on the change of voltages due to the rolling ofthe bearing elements over the measuring point. Thus, an oscillatorymeasuring signal is produced from which it is possible to clearly reador conclude the rotational behavior of the roller drilling tool. It isparticularly advantageous that the rotational behavior of the rollerdrilling tool is determined via a plurality of pulses per revolution.Standstill of a roller drilling tool can thus be detected within a shorttime and corresponding action taken.

An advantageously protected arrangement of the measuring point and atthe same time a measuring signal providing an exact representation ofthe magnitude of the loading of the roller drilling tool and itsrotational behavior is obtained or possible in that according to theinvention the measuring point is associated with the edge of the outerand/or inner race opposite the bearing elements.

In a further advantageous embodiment the measuring point is located in arecess associated with the bearing element path. This provides reliableand exact detection of the loading of the roller drilling tools and oftheir rotational behavior.

It is particularly advantageous with the present invention that asubstantial simplification of the measuring method is achieved and thata constructionally simple device which is easy to attach is provided inwhich, with the same measuring point, at the same time the magnitude ofthe loading of a roller drilling tool can be exactly determined as wellas its rotational behavior. An essential advantage is further thatduring a cutting operation a plurality of pulses can be received andevaluated, thus providing a high information density.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details of the subject of the application will be explained inthe follwing description of the Figures, wherein:

FIG. 1 is a front head view of a drill head of a full-face headingmachine,

FIG. 2 is a cross-section through an antifriction or rolling bearing ofa roller drilling tool with the measuring point in the outer race,

FIG. 3 is a longitudinal section corresponding to FIG. 2,

FIG. 4 is a cross-section of a rolling bearing with the measuring pointin the inner race,

FIG. 5 is a longitudinal section corresponding to FIG. 4 and

FIG. 6 is a graphical representation of a measuring signal producedduring rotation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The drill head 1 illustrated in FIG. 1 is shown schematically andindicates substantially the arrangement of the various rollers 2, 3, 4,5 via which the rock is cut and fragmentated by appropriate applicationpressure.

Each of the individual cutting rollers 2, 3, 4, 5 is equipped with arolling bearing 6 as apparent from the fragment in FIGS. 2 to 5. Betweenthe outer race 7 and inner race 9 a plurality of rolling bearingelements 8 is disposed which are intended to permit a uniform rotationof the cutting rollers 2 to 5. The outer race 7 may be the sleeve of thecutting roller and the inner race 9 the bearing axis of the cuttingroller.

According to FIGS. 2 and 3, disposed in the outer race or ring 7 is arecess 10 which defines the measuring point 11, the measuring pickup ofthe measuring point 11 being a strain gauge 12 which is preferablyadhered in the recess 10. According to FIGS. 4 and 5 this strain gauge12 of the measuring point 11 is accommodated by a recess 10 of the innerrace 9.

Both the construction according to FIGS. 2 and 3 and the constructionaccording to FIGS. 4 and 5 have the recess 10 and the measuring point 11associated with circumferential surface 15 of a bearing race while therolling bearing elements 8 act directly on the other circumferentialsurface 14 of the same race. In each case the strain gauge 12 isconnected to an evaluation unit 16.

FIG. 6 shows graphically the measuring signal produced during rotationof a cutting roller. It is distinguished by changes between extensionregions 17 and stress regions 18, with the reference numeral 19 denotingthe period between two successive maximum force introductions arisingfrom a loading of the measuring point by the rolling bearing elements.

We claim:
 1. The method of monitoring the cutting or wart rollerdrilling tools of a drilling machine used in mining and tunnelconstruction, wherein said roller drilling tools are mounted onanti-friction bearings having bearing races and rolling bearing elementsrunning therebetween, said method comprising the steps of:sensing theloads imposed on said roller drilling tools as well as the rotationalcondition of said tools, and transmitting the sensed values to anevaluation unit, characterized in that said sensing step is carried outon each roller drilling tool by measuring the tangential loading at onlyone measuring point of one of the two bearing races of the associatedanti-friction bearing so as to provide a voltage having a magnitudedependent on the magnitude of said tangential loading and to alsosimultaneously provide oscillation in such voltage magnitude caused bythe rolling bearing elements of said anti-friction bearing moving pastsaid measuring point.
 2. A device for monitoring the cutting or wartroller drilling tools of a drilling machine used in mining and tunnelconstruction, wherein said roller drilling tools are mounted onanti-friction bearings having bearing races and rolling bearing elementsrunning therebetween, said device comprising:means for providing asensing point for each of said drilling tools to measure both theloading imposed on the drilling tool and its rotational condition, andan evaluation unit connected to measuring means, said measuring meansbeing located at only a single measuring point on only one of the twobearing races of the associated anti-friction bearing, said singlemeasuring point corresponding to one of said sensing points, and saidmeasuring means consisting of a strain gauge located near thecircumferential surface of said one bearing race which is opposed to thecircumferential surface of said one bearing race engaged by the rollerbearing elements of said anti-friction bearing.
 3. A device as definedin claim 2 further characterised by said strain gauge being disposed ina recess formed in said bearing race circumferential surface.